The embodiments described herein relate generally to a rotary transformer and, more particularly, to an electrical assembly for use with a rotary transformer.
At least some known rotary transformers include electrical assemblies, such as a rotor and a stator, having at least one ring of active material and at least one winding coupled about the ring. As used herein, the term “electrical assembly” refers to a rotor and/or a stator, and the term “active material” refers to a material having properties that enable a magnetic field to be shaped, i.e., control a direction and/or a magnitude of flux lines in a magnetic field. At least one known rotary transformer includes electrical assembly rings each formed from a plurality of segments. The known segmented electrical assemblies are configured for use in high-power and/or high-frequency applications, such as exciting a generator using 20 kilo-Hertz (kHz) power.
For example, such a known rotary transformer includes ferrite, which has a magnetic flux density of about 500 milli-Tesla (mT), as the active material. Known ferrites that are used in rotary transformers and/or electromagnetic cores contain nickel, zinc, and/or manganese compounds. Such ferrites have a low coercivity and are referred to as soft ferrites. The low coercivity enables the soft ferrites' magnetization to reverse direction without dissipating much energy, i.e. hysteresis losses. Further, soft ferrites' high resistivity prevents eddy currents in the transformers and/or the cores, which also causes energy loss. Because of their comparatively low losses at high frequencies, soft ferrites are extensively used in cores of radio frequency transformers.
Moreover, each segment of active material of the known electrical assembly has a substantially rectangular axial cross-sectional shape, such that a circumferential cross-sectional area of the segment increases as a radius increases. As such, a cross-section of active material of the electrical assembly varies with the radius. Further, along the axial cross-section, each segment of the ring is substantially U-shaped and formed from one or three pieces.
At least some known electrical assemblies include a cable extending from windings of the electrical assembly, outward through the active material of the electrical assembly. In at least some known electrical assemblies, a hole is drilled through the active material to enable the cable to extend through the active material. However, drilling may cause stress in and/or damage the active material. For example, at least some known electrical assemblies include a brittle material as the active material and, as such, drilling may damage or stress the brittle material.